In the electronics industry, a continuing objective is to further and further reduce the size of electronic devices while simultaneously increasing performance and speed. Cellular phones, personal data devices, notebook computers, camcorders, and digital cameras are but a few of the consumer products that require and benefit from this ongoing miniaturization of sophisticated electronics.
An integrated circuit die is a small device formed on a silicon wafer, such as a semiconductor wafer. The integrated circuit die usually is made from a semiconductor material such as silicon or gallium arsenide. Such an integrated circuit die is typically cut from the wafer and attached to a substrate or base carrier for redistribution of interconnects. Bond pads on the integrated circuit die are then electrically connected to the leads on the carrier via bond wires. The integrated circuit die and bond wires are encapsulated with a protective material such that a package is formed. The leads encapsulated in the package are redistributed in a network of conductors within the carrier and end in an array of terminal points outside the package.
Recently there has been rapid development in semiconductor technology and, as a result, semiconductors are becoming smaller, circuitry within semiconductors is becoming increasingly dense to provide higher speeds. As the density increases however, higher power is used in these semiconductor components. Higher power results in greater heat generation in such semiconductors. Thus, heat dissipation is becoming more critical as semiconductor technology develops to address the increasing demand for semiconductors having higher power and speed.
Various techniques may be used to remove or dissipate heat generated by a semiconductor. One passive configuration involves a conductive material in thermal contact with the backside of a packaged die. This conductive material is often a slug, a heat spreader, or an integrated heat spreader (IHS). The heat slug may be formed of a suitable thermally conductive material such as copper, aluminum, composites, or other thermally conductive materials.
The heat slug removes the heat from the integrated circuit and reduces the likelihood of the occurrence of hot spots that can have an adverse effect on the performance and reliability of the integrated circuit. This is achieved by using a wafer scale heat slug system in which the heat slug blank of equivalent size to the integrated circuit is attached to the integrated circuit and the integrated circuit is attached to the substrate.
Interconnection technology is an important aspect of the fabrication of electronic components containing semiconductor devices. The type of interconnection scheme, which is used, can vary widely depending on the desired characteristics of the packaging involved. For example, thin wires are typically used as part of the interconnection, and these may be ultrasonically bonded to the bond pad (sometimes referred to herein as “wire bonding”) or by the formation of solder balls, which, make a direct connection between the bond pad on the chip and a substrate (as in the flip chip process).
Wire bonding generally begins with attaching a semiconductor chip to the surface of a printed circuit board with an appropriate adhesive such as an epoxy. In wire bonding, bond wires are attached one at a time to each bond pad on the semiconductor chip and extend to a corresponding lead or trace end on the printed circuit board. The bond wires are generally attached through one of three industry-standard wire bonding techniques: ultrasonic bonding, thermo-compression bonding, and thermosonic bonding.
An ongoing problem with the use of wire bonding in packaging occurs during a transfer molding encapsulation process of the semiconductor die in what is known as “wire sweep”. Wire sweep results when a wave front of dielectric (commonly a silicon-filled polymer) encapsulation material moving through a mold cavity across the semiconductor die and carrier substrate assembly forces wire bonds to contact adjacent wire bonds and become fixedly molded in such a contacted position after the encapsulation material sets. When wire sweep occurs, a wire bond of an integrated circuit die to a carrier substrate creates a short circuit, which results in a nonfunctional integrated circuit die assembly. Wire bond sweeping may also result in bond wire breakage or disconnection from a bond pad or terminal.
Thus, a need still remains for an improved thermal performance of the integrated circuit that allows consistent placement of the heat slug/spreader, easy attachment of the heat slug by wafer scale method while reducing wire sweep and allowing a free design for the wire bond diagram.
Solutions to these problems have been long sought but prior developments have not taught or suggested any solutions and, thus, solutions to these problems have long eluded those skilled in the art.